The present invention relates to a method and apparatus for purifying and separating fluids and more particularly to a unique and novel method and apparatus for purifying fluids such as water for purposes requiring high purification characteristics, including but not limited to medical endeavors such as is required in kidney dialysis and as is often required in fluid-dependent equipment and procedures in scientific laboratories wherein fluid purification and/or separation is required.
A number of arrangements to purify and/or separate fluids, such as water, have been utilized in the past which have employed the well known principle of reverse osmosis. In accordance with the general principle of osmosis, fluid is passed through a membrane boundary separating two solutions of differing solvent activity. The direction of solvent flow across the membrane boundary under an osmotic gradient or pressure difference is always from the more dilute into the more concentrated solution. In reverse osmosis, solvent flows across the membrane boundary from the more concentrated to the less concentrated solution when pressure application exceeds the osmotic pressure difference. The rate of flow at which reverse osmosis occurs is a direct function of the membrane constant, membrane area and pressure employed and is usually an inverse function of membrane thickness.
The past arrangements which have employed reverse osmosis have, for the most part, been complex and expensive in manufacture, assembly and maintenance, and have presented frequent user problems often resulting in undesirable and possibly dangerous risks to the ultimate user or to the end equipment involved. In the prior art among the numerous fluid processing arrangements known to employ the principle of reverse osmosis for fluid purification purposes, three such known arrangements have employed recirculation of purified fluid received in storage containers from the product side of the reverse osmosis unit back to the feed side of the unit, with one such arrangement even employing an osmotically active chemical treating substance in a back-flush sequence to kill organisms. In this regard, attention is directed to U.S. Pat. No. 3,616,921, issued to Donald T. Bray on Nov. 2, 1971 and U.S. Pat. No. 3,654,148, issued to William E. Bradley on Apr. 4, 1972, wherein, to extend continuous utilization of the purification system, means is employed to pass relatively pure fluid from one or more storage containers either in the form of helical elongated pipes or tanks communicating with the product side of a reverse osmosis unit back to the feed side of the reverse osmosis unit for further purification, U.S. Pat. No. 3,654,148 further including utilization of osmotically active chemicals to obtain osmotic back flushing of the membrane. Attention is further directed to U.S. Pat. No. 4,629,568, issued to George S. Ellis, III, wherein pressure sensing sequences are utilized to cause fluid to flow from storage containers communicating with the product side of a reverse osmosis unit back to the input or feed side. Although these more recent reverse osmosis arrangements have broadly recognized the desirability of fluid recirculation, they have required utilization of elaborate, complex and time-consuming storage containers and conduit recirculating arrangements without concern for or recognition of possible user misoperation and undesirable contaminant build-up on both feed and product sides of a reverse osmosis unit.
The present invention provides a highly efficient and economical reverse osmosis arrangement which recirculates treated fluid from the product side of a reverse osmosis unit directly without storage to the feed side with a minimum of steps and parts and with a minimum of consumer shutdown time, reducing manufacturing, assembly and operation costs and at the same time minimizing user steps, storage requirements and risks of accident to the ultimate consumer. In addition, the present invention provides a reverse osmosis arrangement which facilitates ready adaptation to modular implementation and computer control. As will be seen more fully hereinafter, the present invention permits further ready disinfection and rejuvenation including rinsing of the purifying apparatus and fluid treatment containers assuring a thorough treatment of the reverse osmosis unit, including a shear-like effect by providing a path of fluid flow transverse the path of fluid flow through the membrane of the reverse osmosis unit, without the possible damaging reverse flushing and pulsing requirements of the past and without time-consuming and comparatively complex storage arrangements and, at the same time, with minimum risks to equipment and to ultimate user during treating or cleansing and flushing or rinsing stages. In addition, the present invention provides a unique and novel fluid purification and/or separation arrangement which not only assures full, thorough and efficient disinfection and rejuvenation, including rinsing/flushing of the purifying equipment to permit effective removal of both chemical and microbial contaminants on both feed and product sides thereof, but which minimizes disinfecting and rejuvenating carry-over risks during on-line fluid purifying and/or separation operations. Further the present invention provides a novel disinfection/rejuvenation arrangement, the arrangement including but not limited to disinfection/rejuvenation and flushing treatments being accomplished efficiently and positively through quick connect and flow control mechanisms coupled to the fluid purifying apparatus permitting simple, straightforward, efficient and safer user operations.
Various other features of the present invention will become obvious to one skilled in the art upon reading the disclosure set forth herein.